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Index of Subjects Hi Fred & All, Sept 22, 2012 Explanations of weight/mass usually resemble inconsistent confessions obtained by torture but I guess that is ok now. It seems logical to me that weight should be treated as a special case of F=ma where a in this case is g and F is measured by exerting an equal and opposite force upward to keep the mass from falling. One could then determine the magnitude of mass as F/g and then proceed to work out units of momentum, inertia etc from there. But unfortunately kg has been defined (or perhaps redefined) as a unit of mass which leads to everything being a hopeless muddle. I would try to reform the system of units dealing with weight, mass and distance but I am tied up this afternoon. Yt, Dave Webster, Kentville ----- Original Message ----- From: "Fred Schueler" <bckcdb@istar.ca> To: <naturens@chebucto.ns.ca> Sent: Friday, September 21, 2012 9:19 PM Subject: Re: [NatureNS] Correction; Fw: Velocity of light > Quoting David & Alison Webster <dwebster@glinx.com>: > >> I just dug out my 1st yr Physics (Weber, White & Manning, 1952) and they >> consistently refer to 'speed of light' as opposed to 'velocity of >> light'. Four other sources (1941, 1948, ~1965 &1962) have velocity. > > * indeed, it would be ineffective to purge society, or even literature, > of all who misuse speed/velocity or weight/mass. Or, to bring it closer > to natural history, all who refer to nonhemipterans as "bugs." > > fred. > =============================================== > >> ----- Original Message ----- From: "David & Alison Webster" >> <dwebster@glinx.com> >> To: <NatureNS@chebucto.ns.ca> >> Sent: Friday, September 21, 2012 7:44 PM >> Subject: Velocity of light >> >> >>> Dear All, Sept 21, 2012 >>> The recent discussion about transmission of electricity, reading of >>> HEAT and reading some of Energy... brings to the forefront a question >>> that has nagged me for decades. Perhaps someone can clarify. >>> >>> In the typical elementary physics text we are told that velocity is a >>> vector quantity, and to quote one text "velocity... may be defined as >>> the rate of change of position in a given direction". But "In cases >>> where the direction of motion does not require to be considered , the >>> term speed is employed to express the rate of travelling." >>> >>> Based on the above I would think that the rate of movement of light >>> should be called speed, i.e. speed of light but I think it is always >>> called velocity. >>> For example, if light from the sun is reflected from two 45o mirrors >>> then a beam of light could be directed from the earth back to the sun >>> and, the velocity would then be minus 3 x 10^10 cm/sec. Or if variously >>> scattered or reflected then the velocity, relative to the initial sun >>> to earth direction, would always be less than 3 X 10^10 and after >>> several reflections might be zero. >>> >>> Is there some good reason why the speed of light is termed velocity >>> of light ? Or is it called velocity because the textbook authors forget >>> what they said in chapter one by the time they write chaper eleven ? >>> (And they all copy from each other) >>> Yt, Dave Webster, Kentville >> >> > > > > ------------------------------------------------------------ > Frederick W. Schueler & Aleta Karstad > Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm > Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm > Daily Paintings - http://karstaddailypaintings.blogspot.com/ > South Nation Basin Art & Science Book > http://pinicola.ca/books/SNR_book.htm > RR#2 Bishops Mills, Ontario, Canada K0G 1T0 > presently in Cochrane - 49.06274N 81.02415W - > on the great Ontario Claybelt > (613)299-3107 <bckcdb at istar.ca> http://pinicola.ca/ > ------------------------------------------------------------ > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2221 / Virus Database: 2441/5278 - Release Date: 09/19/12 >
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